Basic properties of equations for physical vapor adsorption in micropores of carbon adsorbents assuming a normal micropore distribution

Abstract

Most typical properties of adsorption equations are considered. Different versions of one equation differ by an energy characteristic expressed by the product of the micropore half-width under the slit model assumptions and the characteristic adsorption energy E 0 (kJ/mol). The adsorption isotherms of ethyl chloride, benzene (reference vapor), and carbon tetrachloride have been studied at 293 K for active carbon samples containing all micropore varieties in the p p 4 range of from 10 −4 to 0.4 for E 0 of from 30 to 9.5 kJ/mol. The value of the energy characteristic k may be between 1 and 12 kJ nm/ mol. The dependence (and sometimes independence) of the equation parameters a 0 0, x 0, and variances on k have been investigated. The effect of the similarity factors β on the calculated degree of adsorption is considered. A more reasonable form of the adsorption equation at k = 10 kJ nm/ mol has been proposed to characterize microporous structures. The role of the molecular sieve effect in characterization of microporous structures is estimated.